1. Field of the Invention
The present invention relates to reinforced flame retardant resin compositions and molded articles.
2. Description of Related Art
In recent years, for resin materials used in devices having optical system units, such as laser beam printers, copiers, projectors, and the like, good flame retardance along with high rigidity and high dimensional accuracy are required. In order to impart rigidity and dimensional accuracy to a resin material, conventionally, an inorganic filler, such as glass fiber, mica, and the like is blended in the resin. While rigidity and dimensional accuracy is improved, however, flame retardance tends to significantly decline in proportion to the blended amount of the inorganic filler, thereby making it extremely difficult to obtain the desired flame retardant property. On the other hand, in order to improve flame retardance, a phosphorus-based flame retardant agent may be blended in the resin. As described above, flame retardance tends to significantly decrease in proportion to the blended amount of the inorganic filler, and in some cases, it may be extremely difficult to obtain any flame retardant property. Thus, in order to obtain a sufficient flame retardant effect, it is necessary to add a large amount of a phosphorus-based flame retardant agent. In such a case, however, the resulting resin material is more likely to lose heat resistance and to drip during combustion. For all of these reasons, it is extremely difficult to obtain a resin material having the desired high heat resistance and good flame retardancy, while maintaining high rigidity and high dimensional stability.
As resin materials for a molded chassis of an optical system unit, a number of proposals have been made to date. For example, as a resin composition suitable for a material for a chassis, a resin composition has been proposed in which a large amount of glass fiber and the like is filled in an aromatic polycarbonate resin of a specific molecular weight (see Related Art 1, for example). A resin composition has also been proposed in which a fiber having a non-circular cross-section and a plate-shaped inorganic filler are blended in an aromatic polycarbonate resin of a specific molecular weight (see Related Art 2, for example). Furthermore, a chassis fixing an optical writing unit molded from a resin composition has been disclosed (see Related Art 3, for example), wherein the resin composition contains an aromatic polycarbonate resin and mica having specific particle size and a thickness, and the resin composition exhibits high rigidity and low anisotropy (see Related Art 3, for example). Furthermore, chassis parts being formed from a polyphenylene ether resin, an inorganic filler in a scaly form, and a phosphorus-based flame retardant agent, have also been proposed, and are said to have excellent dimensional accuracy (see Related Art 4, for example). Furthermore, a resin composition for use in large thin-walled molded parts, such as electrical and electronic equipment components, has been disclosed, the resin composition having excellent impact resistance, dimensional precision, and fluidity, and being composed of a polyphenylene ether resin and a styrene-based resin having specific intrinsic viscosity, glass fiber, and a plate-like filler (see Related Art 5, for example). Resin compositions suitable for a molded chassis have also been disclosed, the resin compositions being composed of a thermoplastic resin, such as a polyphenylene ether-based resin and a polycarbonate-based resin, along with a certain amount of an organic phosphorus-based flame retardant agent and inorganic filler, such as talc, mica, and the like (see Related Art 6).
[Related Art 1] Japanese Patent Laid-open Publication No. H5-287185
[Related Art 2] Japanese Patent Laid-open Publication No. H6-207189
[Related Art 3] Japanese Patent Laid-open Publication No. H9-12733
[Related Art 4] Japanese Patent Laid-open Publication No. H8-115588
[Related Art 5] Japanese Patent Laid-open Publication No. H8-183902
[Related Art 6] Japanese Patent Laid-open Publication No. 2004-315645
It is hard to say, however, that the above-mentioned conventionally disclosed resin compositions and molded articles using the same fully satisfy all the requirements such as high heat resistance, high rigidity, high dimensional accuracy, and good flame retardant property. There is room for further improvement, especially as a resin composition used for chassis parts for optical system units. Thus, an object of the present invention is to provide a resin composition that has achieved a good balance of high heat resistance, high rigidity, high strength, high dimensional accuracy, and good flame retardancy.